Oceanic Control of Monsoon Intra-seasonal Oscillations in the Tropical Indian Ocean and the Bay of Bengal (MISO-BOB)

An Air-Sea Interaction Initiative: This Initiative is Fully Subscribed

Our current predictive skill of the monsoon is poor on weekly to monthly timescales, yet improved prediction would benefit the billions of people that inhabit the nations bordering the northern Indian Ocean as well as the safety of ships at sea that work in or transit through this area. The upper ocean stratification in the Bay of Bengal is strongly controlled by the salinity structure, resulting in complexities in the upper ocean temperature and heat content distribution. The heat content and stratification impacts the air-sea fluxes, thus coupling the atmospheric and Oceanic boundary layers at multiple-scales. Previous work has shown that coupling with the oceans in coupled models improves weather predictions, but the mechanisms and the required coupling approach are yet to be identified. This new proposed observational and modeling work is timely both in terms of our current state knowledge and overlap with funded atmospheric and oceanic measurement programs in India.

The active and break cycles determined by Monsoon Intra-seasonal Oscillations (MISO) strongly modulate rainfall, sea surface temperature, heat fluxes and winds and (presumably) surface currents in the northern Indian Ocean. The northern Indian Ocean (Bay of Bengal and Arabian Sea) show strong coupling at 10-90 day time scales. Currently, the MISO represents a primary challenge to sub-seasonal weather prediction and accurate simulation of upper ocean temperature and salinity structure. Coupled regional climate models have shown that the ocean plays an important role in setting the propagation speed and intensity of the MISO; but our current in situ knowledge of the MISO in the sub-surface ocean is comprised of coarse resolution information from the ARGO float program and the RAMA mooring array in the Bay of Bengal. These data show clear signatures of MISO in both salinity and currents in the Northern Indian Ocean. Further, taken together with results from coupled regional ocean-atmosphere models, they lead to a number of important unanswered questions that ultimately effect predictability of weather and the upper ocean temperature and salinity structure.

Goal

This motivation results in the following primary objectives of this program:

Understanding the ocean influence on the intensity and propagation speed (roughly 1 degree north per day) of the coupled ocean-atmosphere MISO signal

Determining how the large-scale upper ocean variability in the Northern Indian Ocean, which includes shallow salinity-driven mixed layers in the north and deeper mixed layers in the south, influences the MISO signal

Evaluating how the submesoscale and mesoscale perturbations and processes that govern the oceanic background state communicate with and influence the MISO

Integrate data and models to determine the spatial and temporal scales at which atmospheric and oceanic signatures need to be coupled to accurately capture the MISO propagation

Partnerships: MISO BOB will be a balanced program between at-sea observations, forecast modeling and data assimilation. Collaborations with our partners and hosts will provide much of the atmospheric framework; thus, this call for planning letters is largely focused on efforts to understand the oceanic influence and the role process models, forecast models and ocean data assimilation can play in answering the above questions.

Request for Planning Letters

The first step in the DRI process is for prospective investigators to prepare planning letters. The purpose of the planning letters is to allow investigators to submit a short (three pages maximum) summary of their ideas on this topic for ONR to evaluate, provide technical feedback and indicate whether a full proposal would have a reasonable chance of success.

Important Dates

September 30, 2016: Last date to submit planning letters (submit by email)October 1, 2016: Last date ONR will respond to all submitted planning letters and requests for proposalsOctober 30, 2016: Earliest anticipated commencement of awards made with FY17 funding - dependent on USG budgetary process